function add_a(x, y) {
	console.log(arguments.login);
	console.log(JSON.stringify(arguments));
	const res = Array.from(arguments);//伪数组转换为数组
	return x + y;
}
console.log(add_a(1));
console.log(add_a(1, 2));
console.log(add_a(1, 2, 3));


